Refining of petrolatum



Jah. 13; A1942.

C. E. ADAMS ETAL REFINING 0F PETJROLAATUM l Filed Sep't. l0, 1958 NN ummm@ Patented Jan. 13, 1942 REFININ G OF PETROLATUM Chester E. Adams, `,Highland, and Arthur B. Brown, Hammond, Ind., and David W. Bransky, Chicago, Ill., assignors to Standard Oil Company, Chicago, Ill.,` a corporation of Indiana Application september 1o, 193s, serial No. 229,250 s claims. (ci. 19e- 21) This invention relates to the refining of petrolatum, and it pertains more particularly to the production of petrolatum with new and improv-ed properties by means of. reningprocesses employlng propane.

Crude petrolatum produced from Pennsylvania residuums or deasphalted lVId-Continentresiduums (steam-renned stocks, cylinder stocks,

etc.) is associated with undesirable oils, color bodies or other impurities which must be removed if the finished product is to meet the rigid specifications of the trade, of U. S. Pharmacopoeia, etc. The finished petrolatum must have a certain color or absence of color (depending upon the grade), and it must meet rigid requirements as to melting point, penetration, translucency or` acteristics, to improve the stability of the product,

particularly its stability in sunlight and at high temperatures, to improve the viscosity, melting point and penetration characteristics, and to improve the: general appearance and quality oi :linished petrolatums. A further object is to obtain maximum yields of a superior grade of petrolatum from a given charging stock, and to improve the efciency and efectiveness of the petrolatumreiining process. Other objects will be apparentas the detailed description of the invention proceeds.

In accordance with current practice the undesirable oils,` color bodies or impurities associatedv with petrolatum` are washed" out Aof the crude petrolatum with naphtha or equivalent hydrocarbon washing oil `in a series of settling operations, the crude product being dissolved in naphtha and settled therefrom in each of a plurality `of stages so that the oils, color bodies, and impurities are transferred from the petrolatum to the naphtha or Wash oil. This process requires considerable time and equipment rand it is subject to the further disadvantage that the highly desirable low melting point waxes tend to dissolve in the wash oil so that the finished petrolatum does not have the desired consistency and melting point versus `penetration relationship. An object of our invention is to provide a t process which will make possible the retention of all of the low melting point wax components and in which the concentration of these low melting point waxes may be even increased by the rev moval of certain less desirable high melting point components. l

Although acid-treating has been a common refinery practice forpetroleum oils since the beginning of the industry, this acid-treating step has never been successfully used on petrolatum waxes because of the inherent emulsication diiculties and the impossibility of settling the sludge from treated wax. We have discovered that petrolatum may be successfully and economically treated with sulfuric acid and that the treatment may be elected in the presence of from 4 to 10 volumes of propane at a temperature of about 70 to 120 F. The propane makes it possible to effect sludge settling at the desired treating temperature.

While we do not limit ourselves to any theories, it may be that because of the preferentially pre cipitating action of the propane, the distribution ratio between the acid sludge vand the remaining petrolatum and oil is so changed that the acid becomes a much better solvent for the color bodies. The propane tends to throw out any undesirable, high molecular Weight and therefore high melting point components, and such components may either be settled and withdrawn with the acid sludge or may be settled and withdrawn in a preliminary settler. The propane serves to prevent any local overheating by absorbing its heat of vaporization wherever local overheating might otherwise occur.

Another feature of our invention is the reduction in clay costs which is eected by the acid treating of the petrolatum in propane solution, The large increase in clay yields makes the process particularly attractive from a commercial standpoint.

Briey, our invention contemplates the solution of petrolatumin-propane, either with or without a preliminary settling step for removing high molecular Weight components and resnous materials, followed by acid treating in propane solution at a temperatureof about to 120 F. The acid-treated petrolatum may be neutralized and/or clay treated in the propane solution, or it The invention will be more clearly understood from the following detailed description read in connection with the accompanying drawing which forms a part of the specification and which is a flow diagram of our improved petrolatum treating system.

The petrolatum may be obtained from any Pennsylvania or deasphalted mixed base crude by any known dewaxing method such as centrifuging, cold settling or ltration from chilled propane solution. The crude petrolatum from storage tank I is withdrawn through steam discharge heater II, line I2 and pump I3 to mixer I4 in which it is mixed with propane from storage tank I5, line I0 and pump I'I. Temperature control may be effected in the mixer by a suitable heating or cooling means, or the mixture may be passed through a separate heat exchanger I8 in order to effect complete solution of the desirable components of the crude petrolatum in the propane. The exact temperature of the mixture will vary with the particular stock undergoing treatment and with the qualities of the product to be produced, but the temperatures will generally be within the range from about 70 to 120 F. The popane ratio will vary from about 4 to 10 volumes per volume of crude petrolatum.

The solution from heat exchanger I 8 may be introduced through line I9 into settler 20 for removing undissolved high melting point wax fractions and any residual resinous or asphaltic materials, which separate out as a lower phase and may be withdrawn through line 2i to a suitable depropanizing or recovery unit. The propane solution from settler 2l] is withdrawn through line 22 to mixer 23. In most cases the settler 20 may be dispensed with .and the propane solution may be introduced directly from line I9 through line 24 into mixer 23.

Sulfuric acid from storage tank 25 is introduced by pump 20 into mixer 23. We prefer to use an acid concentration of 1041/2 but acid as low as 93% concentration may be employed. For example 1/2 pound of 98% acid per gallon of petrolatum in 10 volumes of propane at 120 F. gave a treating and washing yield of 88%, increased the gravity of the petrolatum from 26.9 to 28.9, and improved the color from a true color of 1800 to a true color of 114. Ordinarily we prefer to use about 7% to 15% by weight (based on petrolatum) of about 98% to 1041/2% acid, with a propane-to-oil ratio of about :1', although the amount of acid will depend upon the amount and character of oil in the particular stock and may vary from about .1 pound per gallon to 2.0 pounds per gallon.

The mixture of acid and propane-wax solution is then introduced through line 2l to sludge settler 28 which is provided with the conventional funnel-shaped baiile 29. Propane may be vented through line 30 to the propane recovery system and a suitable pressure-controlled valve in this line may be used to maintain a predetermined pressure, and hence a predetermined treating temperature which will usually range from about 70 to about 120 F. Generally speaking, we prefer to effect the treating at relatively low temperatures. We have found that with 2 pounds of 95% acid and 4 volumes of propane, treating at 70 F. resulted in the separation of a waxy sludge from a sour petrolatum which, when contacted with '7% of clay (Attapulgus) and mixed with white oil gave a melting point of 104 and a penetration at 77 F. of 184. When the treating temperature was raised to 81 F. we

found that the melting point increased to and the penetration at 77 F. increased to 193. When the acid treating was at 10U-110 F, the melting point of the nished petrolatum ranged from 111 to 114 and its penetration at 77 F. ranged from 185 to 196, depending upon the quantity of white oil blended therewith. From these and other data We find that by treating within the range 'l0-85 F. in propane, a petrolatum is obtained which has a lower melting point for the same penetration than would be the case if the treatment were carried out at 100 F. Petrolatums having lower melting points for given penetrations add a better translucency. By treating in propane at 'l0-85 F., a single-step process, less white oil is required to bring the petrolatum to any desired penetration than would be required using the old two-step settling process. The color improvement for an equal quantity of acid appears to be substantially the same over the stated range of treating temperaturesa crude petrolatum darker than 8 N. P. A. after treating with 2 pounds of acid and neutralizing gave a color of about 3 N. P. A.

As hereinabove indicated, our process makes possible the regulation and control of melting point-penetration relationships of the iinished petrolatum. It also makes possible the regulation and control of translucency and general appearance, and it provides a flexibility which enables the production of a petrolatum which will meet any particular speciiications.

As above indicated, high melting point wax components may separate with the sludge, and this waxy sludge mixture may be withdrawn thru line 3l to a suitable depropanizer unit, the acid and reaction products and hydrocarbon content of the sludge mixture being recovered by conventional means.

The sour petrolatum solution is withdrawn from the settler thru line 32 to mixer 33 wherein it is mixed with caustic solution from tank 34 and pump 35. The spent caustic is settled from the mixture in settler 36 and the neutralized solution is withdrawn through line 37 directly to still 38 or through line 39, clay treating chamber 40 and line 4I to still 38. We may, of course, pass the sour petrolatum solution directly through line 42 to clay-treating chamber 40, employing the clay as a neutralizing as well as a decolorizing agent.

We prefer to treat with clay by percolation at a temperature of about t0 200 F., preferably at about to 170 F. The clay may, however, be introduced as a slurry into the sour or neutralized propane solution, and introduced therewith to the still, which may be either a shell still or pipe still.

Propane from the still, or from the flash drum or fractionator if a pipe still is used, may be returned thru line 43 and condenser 44 to storage tank I5. The finished petrolatum is Withdrawn from the base of still 38 (or flash drum or fractionator, etc.) to storage or for further treatment. This rened petrolatum may be washed with naphtha or wash oil in the conventional manner and blended with White oils to produce very white, high-grade petrolatums, but for most purposes this washing step is not necessary. Also, the percolation or clay treating may be effected after propane removal and after Washing, but the most eiective procedure is that hereinabove stated.

We have found that acid-treated petrolatums have a. much better color stability in sunlight and 4. The method of refining crude petrolatumy at high temperatures than untreated petrolatums. The clay costs are markedly reduced. The translucency and general appearance, the melting point-penetration characteristics, and the quality of the petrolatums are greatly improved.

The method hereinabove described makes possible the use of higher viscosity blending oils than have heretofore been` used for meeting specifications, and this also helps improve the quality of the finished product. The white oils used for obtaining a penetration of about 190 to 200 may be in amounts of about 50% to 55%, but this will of course depend on'the nature of the crude petrolatum and on the specifications to be met.

The term propane as used herein is intended to cover not only this hydrocarbon but other normally gaseous hydrocarbons such as ethane, isobutane, normal butane, etc. and mixtures thereof,particularly those mixtures that have a boiling point at atmospheric pressure of about to 50 F.

While we have described in detail a preferred embodiment of our invention we do not limit ourselves to any of said details except as defined by the following claims which should be construed as broadly as the prior art will permit.

We claim:

1. The method of improving the color, melting point-penetration characteristics, translucency, color stability and general appearance of petrolatum which comprises dissolving a low grade petrolatum in propane, removing waxes, resins and color bodies from said solution at a temperature of about 70 to 85 F. without removing low melting point wax components, treating the remaining low melting point wax components in propane solution with concentrated sulfuric acid at a temperature of about 70 to 85 F., and contacting said wax with Aclay.

2. The method of making a high quality petrolatum from a low grade petrolatum wax mixture separated from a mixed base petroleum oil, which method comprises blending said low grade wax mixture with about 4 to 10 volumes of liquid propane, acid-treating the mixture at a temperature of about 70 to 85 F., using about 0.1 to 2.0 pounds of sulfuric acid of about 93% to 1041/% concentration per gallon of petrolatum, removing insoluble wax, resins, sludges and impurities from the propane solution, treating the remaining dissolved low melting point waxes with clay and distilling the propane from the treated low melting point petrolatum waxes.

3. The method of improving the melting pointpenetration characteristics and translucency of low grade petrolatums which comprises treating said petrolatums in propane solution with sulfuric acid at a temperature of the order of 70 to 85 F.

wax which comprises dissolving it in 4 to 10 volumes of propane, acid treating it in propane solution at a temperature of about to 85 F., using about .1 to 2.0 pounds of acid of 93% to 1041/2`% concentration per gallon of petrolatum, removing insoluble wax, resins, sludges and impurities from the propane solution and treating the acid-treated petrolatum with clay.

5. 'Ihe method of eliminating from crude petrolatums the color bodies and impurities norvmallyassociated therewith which comprises dissolving said crude petrolatums in about 4 to 10 volumes of propane and treating said solution with about 0.1 to 2.0 pounds of sulfuric acid (of about 93% to 1041/2% concentration) per gallon of petrolatum at a temperature of yabout 70 to F. and subsequently neutralizing the acidtreated petrolatum.

6. The method of improving the color, melting point-penetration characteristics and stability of petrolatums which comprises dissolving said petrolatum in propane at a temperature of about 70 to 120 F., removing waxes, resins and color bodies insoluble in said solution without removing low melting point wax components, acidtreating the solution in propane solution at a temperature of about 70 to 85 F., treating the acid-treated petrolatum with clay, removing the propane from the treated petrolatum and blending said treated petrolatum with a viscous white oil.

7. The method of refining crude petrolatum which comprises dissolving it in from 4 to 10 volumes of propane, acid treating it in the propane solutionl at a temperature of about 70` to 85 F.,

using about .1 to 2.0 pounds of sulfuric acid of 93% to 104% concentration per gallon of petrolatum, separating the propane insoluble material from the acid-treated propane solution, neutralizing the acid-treated propane solution with caustic and subsequently treating the neutralized petrolatum with clay.

8. The method of refining crude petrolatum which comprises dissolving it in from 4 to 10 volumes of propane, acid treating it in the propane solution at a temperature of about 70 to 85 F., using about .1 to 2.0 pounds of sulfuric acid of 93% `to 104% concentration per gallon of petrolatum, separating the propane insoluble material from the acid treated propane solution, neutralizing the acid treated propane solution with caustic, removing the propane from the neutralized solution and subsequently treating the neutralized petrolatum with clay.

CHESTER E. ADAMS. ARTHUR B. BROWN. DAVID W. BRANSKY. 

